Viral diseases caused by serious acute respiratory syndrome (SARS) virus, avian influenza viruses, foot-and-mouth disease virus, new kinds of influenza viruses, etc. arouse social problems one after another. Originally, viruses have limited host ranges, and it is usual for some viruses to infect mammals only and for other viruses to infect birds only. However, avian influenza viruses have a wide range of hosts and can infect not only birds but also mammals, and there is hence a possibility that some avian influenza viruses might infect human beings also. At present, avian influenza virus type H5N1 infests Asia and Europe, and there is a fear that a virulent influenza virus may appear as a result of a variation of that type of virus as a base to cause a pandemic.
There is hence a desire for development of a material which shows antiviral properties or a material capable of imparting antiviral properties, as a measure against such a pandemic. In addition, antiviral products for not only medical facilities such as hospitals, health centers, and protective institutions but also general public facilities and even families have come to be desired in preparation for a viral pandemic.
Patent document 1 discloses a sheet obtained by mixing a composition for imparting antiviral properties which includes either regenerated collagen fibers or a regenerated collagen powder with a polyurethane resin and coating a flexible PVC sheet with the mixture.
According to the definite cases concerning countries and human beings of the occurrence of avian influenza (H5N1) reported by the Ministry of Health, Labor and Welfare of Japan, highly pathogenic avian influenza has occurred in a wide range of regions including Asia, Europe, the Middle East, and Africa since November, 2003. Infections of avian influenza which have been ascertained include not only ones from fowls to fowls but also ones from fowls to primates. With respect to human beings, in particular, six hundred and odd persons were infected so far and at least 350 of these died. Furthermore, there is a possibility that avian influenza viruses might undergo a variation through crossing with a human influenza virus or even by themselves to become virulent.
Consequently, techniques and products which are capable of rapidly inactivating viruses are eagerly desired. Of such products, interior decorative building materials for use in, for example, medical facilities, which are expected to undergo contacts with viruses, are especially desired to inactivate viruses. In particular, wallpapers, which occupy a large part of construction areas, are highly desired to have antiviral properties.
For wallpapers, vinyl-chloride-based resins such as vinyl chloride resins and olefin-based resins are frequently used. In particular, vinyl-chloride-based resins are used for most wallpapers because vinyl-chloride-based resins are inexpensive and have various excellent properties and because the wallpapers thereof can be made to have an attractive appearance by embossing the wallpapers to form fine recesses and protrusions in the surfaces thereof.
Meanwhile, patent document 2 proposes a method in which a vinyl/maleic anhydride copolymer to which metal ions have been fixed is used as a material for imparting antiviral properties to fibers. However, there is no statement therein concerning any technique for applying the invention to a wallpaper constituted of a poly(vinyl chloride)-based resin or to an interior decorative sheet.
An antiviral agent is an agent which deprives viruses of the infectivity and thereby prevents the viruses from invading cells. Known as such an antiviral agent is, for example, slaked lime. In patent document 3, a resinous coating film containing slaked lime is disclosed.